Reduction of nitro compounds.



UNITED STATES PATENT GFFI'CE.

MAX BUOHNER, OF MANNHEIM, GERMANY.

REDUCTION OF NlTRO COMPOUNDS.

SPECIFICATION forming part of Letters Patent N 0. 700,672, dated May 20,1902.

Application filed September 24, 1900. Serial No. 30,968. (No specimens.)

To all whom it may concern:

Be it known that I, MAX BUCHNER, a citizen of the Empire of Germany,residing at Mannheim, in the Empire ofGermany, have invented certain newand usefuldmprovements in the Reduction of Nitro-Gompounds; and I dohereby declareth efollowing to be afull, clear, and exact description,of the invention, such as will enable others skilled in the art to whichit appertains to make and use the same.

This invention relates to the reduction of nitro compounds, withparticular reference to the employment of an electric current for suchpurpose.

In my application for Letters Patent of the United States, Serial No.737,494, filed November 18, 1899, I have described a process ofelectrolytic reduction of nitro compounds which consists, essentially,in causing an electric current to pass through the nitro compound placedin the cathode-space of an electrolytic cell in the presence of tin, thetin being in acid solution. Under that process the reduction of thecompound employed and the recovery of the tin employed take placesimultaneously. In the course of my further experiments and researchesin this direction I have found that this method may be carried out alsoby means of copper; and my present invention consists in the reductionof nitro compounds by causing the electric current to pass through suchcompounds in acid solution and in the presence of copper ions and insuch further features as will be hereinafter set forth, and pointed outin the claims. Just as in the process set forth in my aforesaidapplication, No. 737,494, the cathode material is unimportant, since thesame serves merely to convey the curren t, while the process ofreduction is solely dependent on the presence of the metal named in thecathodechamber. Itis,moreover,iinmaterial whether a salt of copper ormetallic copper in a finelydivided condition is added to the electrolytein the cathode-chamber. In both cases the reaction proceeds over or byway of the regenerated or recovered metal or metal ion. There exists inthe two cases merely a difference in the form of regeneration of themetal or metal salt, which form is governed by the magnitude of theelectrolytic dissolving tension of the element in question. If the sameing of any suitable indifferent metal.

is small, as in the case of copper, under the present invention, themetal after having entered the ion condition, and thus carried out thereduction, is directly restored to the metallic from the ion condition.

I will now describe my invention in detail with the aid of two examplesembodying what I consider the preferable method of carrying the sameinto effect.

1. Reduction of nitrobenze-ne by the addition of cuprous chlorid t0 thecathode electro- Zyte.An electrolytic element or battery is divided intoa cathode and an anode chamber by a suitable diaphragm. The electrolyteof the anode-space consists of a ten-per-cent. solution of sulfuricacid, the anode consist- The cathode-chamber contains a cylindricalplati num electrode and is charged with a mixture of five hundred partsjby weight, of fuming hydrochloric acid, five hundred parts, by weight,of water, one hundred and twentythree parts, by weight, nitrobenzene,and thirty parts, by weight, of cuprous chlorid. The nitrobenzene ismaintained is suspension by a rapidly-revolving agitator or stirrer andwhen consumed is replaced by a fresh supply, thus making the processcontinuous. During the course of the process the mixture ispreferablycooled. Thecurrentintroduced has a density of about nineteenhundred am peres per square meter, and this current is maintained untilregular liberation of hydrogen takes place and becomes visible. Afterthe process of electrolysis is completed the copper of the cuprouschlorid will be found to have been separated in the form of finemetallic sponge, and no copper will be found in the cathode electrolyte.The nitrobenzene will be converted almost quantitatively into anilinchlorid, from which the base may be isolated by well-known methods.

:3. Reduction of nitrohenzene by addition of copper-ponder to thecathode electrolyte-The process is carried out in the same manner asunder Example 1, with the difference that instead of thirty grams ofcuprous chlorid twenty grams finely-divided metallic copper are added tothe cathode electrolyte.

What I claim, and desire to secure by Letters Patent of the UnitedStates, is-

1. The process of reduction which consists in introducing a reduciblesubstance into the acid electrolyte contained in the cathodespaces of anelectrolytic cell and passing a current throughgthe same in the presenceof copper, the electrolyte being one capable of reducing the copper tothe ion condition.

2. The process of reducing a nitro compound which consists inintroducing such compound into the acid electrolyte contained in thecathode-spaces of an electrolytic cell and passing a current through thesame in the presence of copper, the electrolyte being one capable ofreducing the copper to the ion condition.

3. The process of reduction which consists in introducing a reduciblesubstance into the acid electrolyte contained in the cathodespace of anelectrolytic cell and passing a current through the same in the presenceof a copper cathode,the electrolyte being one capable of reducing thecopper to the ion condition.

4. The process of reducing a nitro compound which consists inintroducing such compound into the acid electrolyte of the oathode-spaceof an electrolytic cell and passing an electric current through the samein the presence of a copper cathode, the electrolyte being one capableof reducing the copper to the ion condition.

5. The process of reduction which consists in introducing a reduciblesubstance into an acid cathode-bath containing a compound of copper andpassing an electric current through said bath, the electrolyte being onecapable of reducing the copper to the ion condition.

6. The process of reduction which consists in introducing a reduciblesubstance into an acid cathode electrolyte and passing an electriccurrent through the same in the presence of copper and at the same timestirring and cooling, the electrolyte being one capable of reducing thecopper to the ion condition.

7. The process which consists in introducing a substance which isreducible to an amin into an acid cathode-bath in which is arranged acopper cathode and passing an electric current through the same.

S. The process which consists in introduc- Y ing a substance which isreducible to an amin into an alcoholic-acid cathode-bath in which isarranged a copper cathode and passing an electric current through thesame while stirring and cooling.

9. The process which consists in introducing a nitro compound to bereduced into arcathode-bath containing hydrochloric acid and in which isarranged a copper cathode to the action of an electric current.

10. The process which consists in introducing a nitro compound into acathode-bath containing a cuprous compound and hydrochloric acid andhaving a cathode arranged therein and passing an electric currenttherethrough.

11. The process which consists in introducing a nitro compound into acathode-bath containing hydrochloric acid and a cuprous salt and havinga cathode arranged therein, and passing an electric current therethroughwhile stirring and cooling.

In testimony whereof I affix my signature in presence of two Witnesses.

MAX, BUCHNER.

\Nitnesses:

JACOB ADRIAN, FRITZ AcH.

